A great deal is known about many drugs, how they act and where they localize in the body. Investigators have sought many ways of utilizing this information so the drugs may be made into radiopharmaceuticals and used in the diagnosis of disease. In this project a new method has been devised, which from preliminary data appears successful. Chemicals known as chelates which bind metal ions have been synthetically incorporated into precursors of biologically active molecules to create a radioactive analog of the parent compound. The metal ions used are specially chosen radioisotopes which allow the distribution of the radiolabeled molecule (radiopharmaceutical) in the body to be recorded as an image, thus visualizing the target organ and observing its function. Completion of this project will result in the synthesis of a cross-section of radiolabeled, biologically active drugs for the study of human physiology in health and disease. The drugs chosen are ones known to accumulate in the myocardial muscle and in certain forms of cancer. Successful completion of this work will be of value in the diagnosis of heart disease and cancer.